Rapid diagnosis of mycobacteria, especially Mycobacterium tuberculosis and Mycobacterium avium complex, using BACTEC 460 TB system

Abstract

Fourty-five sputum specimens collected at the National Sanatorium Hiroshima Hospital were subjected to cultivation using either BACTEC 460 TB System (BACTEC method; Becton Dickinson Co., Towson, Md., U.S.A.) or 3% Ogawa egg medium. Test sputum was treated with four volumes of 4% NaOH for approximately two minutes, after which 0.1 ml of the treated sputum was immediately inoculated onto 3% Ogawa egg medium. After neutralizing the remaining pretreated sputum with 1N HCl, and diluting with 1/15 M phosphate buffer PB; pH 6.8), it was then centrifuged at 3,000 rpm for 20 min and the sediment was suspended in 1.5 ml of PB. Volumes of 0.5 ml each were inoculated into BACTEC 12B medium (4 ml), containing PANTA for prevention of contamination and POES for promoting the growth of mycobacteria. In the BBCTEC method, bacterial growth was measured in terms of increases in the Growth Index (GI) values which were determined by the amount of 14CO2 released from the 14C-labelled palmitate during cultivation at 37 degrees C (positive growth; GI greater than or equal to 50). Moreover, rho-nitro-alpha-acetylamino-beta-hydroxy-propiophenone (NAP)-sensitivity testing was done by transferring a part of the BACTEC 12B culture showing positive growth to a NAP vial, and thereafter subjected to further cultivation.(ABSTRACT TRUNCATED AT 250 WORDS)